Modified acrylonitrile polymer fibers

ABSTRACT

Modified acrylonitrile polymer fibers having wash-resistant antistatic properties can be obtained by treating acrylonitrile polymer fibers containing at least 40 percent by weight of acrylonitrile with a copolymer consisting of 60 - 98 percent by weight of a vinyl compound having a general formula of   (WHEREIN R1 is hydrogen or methyl group, n is an integer of 3 to 50 and R2 is alkyl group having one to 20 carbon atoms or alkylphenyl group having one to 20 carbon atoms in alkyl moiety) and 40 - 2 percent by weight of acrylonitrile.

United States Patent 1 Shichijo et al.

Nov. 6, 1973 MODIFIED ACRYLONITRILE POLYMER v FIBERS Appl. No.: 98,891

Assignee:

Foreign Application Priority Data Dec. 18, 1969 Japan 44/101285 U.S. Cl.....'l17/138.8 UA, 117/7, l17/139.5 A, 117/161 UN, 252/89, 260/855 R Int. Cl D06m 15/36, B32b 27/30 Field of Search ll7/l39.5 A, 138.8 UA, 117/161 UN; 252/89; 260/855 R References Cited UNITED STATES PATENTS 7/1970 Wolf et al.,... -1 17/1395 A l/1958 Suen et a1. 117/161 UN X 3,056,695 10/1962 Von Brachcl et al. 1 17/1388 UA X 3,333,983 8/1967 Selle! ll7/l38.8 UA X 3,366,613 l/l968 Kcllcy ll7/l39.5 A X Primary Examiner-Ralph Husack Attorney.lames E. Armstrong and Ronald S. Cornell [57] ABSTRACT Modified acrylonitrile polymer fibers having washresistant antistatic properties can be obtained by treating acrylonitrile polymer fibers containing at least 40 percent by weight of acrylonitrile with a copolymer consisting of 60 98 percent by weight of a vinyl compound having a general formula of (wherein R is hydrogen or methyl group, n is an integer of 3 to 50 and R is alkyl group having one to 20 carbon atoms or alkylphenyl group having one to 20 carbon atoms in alkyl moiety) and 40 2 percent by weight of acrylonitrile.

4 Claims, N0 Drawings 1 MODIFIED ACRYLONITRILE POLYMER FIBERS SUMMARY OF THE INVENTION This invention relates to modified polyacrylonitrile polymer fibers having permanent antistatic property.

BACKGROUND OF THE INVENTION With regard to the processing of polyacrylonitrile polymer fibers for permanent antistatic property, there have been proposed heretofore several methods but all of these various drawbacks and cannot be called completely successful. The prior test processes are so complicated that a large scale production is difficult even when they are industrialized. Deterioration of fiber properties and handling result, and difficulties occur during the processing steps in the production of ultimate commerical goods. Those having commerical value are generally not obtained or the antistatic propv erties of the ultimate commercial goods are unexpectedly bad.

It is an object of the present invention to provide polyacrylonitrile polymer fibers having superior commercial value in which the above-mentioned drawbacks of the conventional methods have been overcome and yet the advantages of conventional poly-.

acrylonitrile are retained.

The abovementioned object can be attained by the acrylonitrile polymer fibers containing 40 percent by weight or more of acrylonitrile, obtained by treating the acrylonitrile polymer fibers with a copolymer consisting of 60 98 percent by weight of a vinyl compound having a general formula of (wherein R is hydrogen or CH n is an integer of'3 50 and R is alkyl group having one to carbon atoms or alkylphenyl group having one to 20 carbon atoms in alkyl moiety) (said vinyl compound will be abbreviated hereinafter as antistatic monomer) and 40 2 percent by weight of acrylonitrile.

The antistatic monomer can be synthetized (l) by the esterification reaction of an addition product of ethylene oxide and the corresponding aliphatic alcohol or alkylphenol with acrylic acid or methacrylic acid, (2) by ester-interchange reaction of the same with an ester of acrylic acid or methacrylic acid of (3) by dehydrochloric acid reaction of the same with acrylic chloride or methacrylic chloride.

Such a monomer can be polymerized by itself or relatively easily by the use of a suitable radical polymerization initiator. However, when the homopolymer of such a monomer is water-soluble, its wash fastness is poor and the handle of treated fibers is not as preferable. In contrast, in case of a copolymer of an antistatic monomer and acrylonitrile, the antistatic effect of treated fiber was wash fastness, products having superior handle can be obtained and no troubles are developed in spinning step despite of its water-soluble property and the lack of cross linking agent. This is really a surprising fact because most of water soluble antistatic agents, in general, have been considered to be liable to be removed during laundering and dry cleaning. The term water soluble property as used herein includes not only that possessed by those agents which give true solutions but also that possessed by those which give colloidal solution without the aid of a dispersing agent when added to water. Thus, it is to be understood that an aqueous solution of the copolymer in which a greater part of the copolymer is dissolved but the slightest amount of higher molecular weight portion of the same copolymer is not perfectly dissolved, giving a slight turbidity, is also useful in the treatment of the present invention as above-mentioned. The watersoluble property of the copolymer is very advantageous because no other organic solvent is necessary and water, which is the most inexpensive solvent, can be used in the treatment of fibers. Further, this property is advantageous also from the point of accident prevention and more uniform adhesion attainable at the time of processing of fibers. Accordingly, a great benifit can be attained in commercial operation. With regard to the reason of wash fastness of such copolymers, it is believed to be in the fact that one component of the copolymer is acrylonitrile and the affinity between the copolymer and the acrylonitrile type fibers is strong. Further compared with a water-insoluble polymer, the copolymer has a stronger affinity to acrylonitrile type fibers and superior wash-fastness.

The synthesis of copolymers consisting of an antistatic'monomer and acrylonitrile can be effected by the use of any of conventional radical polymerization methods but what is important here, is the proportion of antistatic monomers vs. acrylonitrile. This has influence upon polymerization properties (such as polymerization degree, conversion of polymer, etc.) solubility of copolymers, handle of treated fibers, effectiveness of function, etc. For example, when the content of acrylonitrile is large, water-solubility is reduced and handle is reduced. On the other hand, when the content of acrylonitrile is small, the tendency is that polymerization property is lessened, and wash fastness of the antistatic effect is inferior. From the foregoing reason, the compositions consisting of 98 percent by weight of antistatic'monomer, and 40 2 percent by weight of acrylonit'rile are preferable and those of 70-90% by weight of antistatic monomer and 30 10 percent by weight of acrylonitrile are more preferable in the present invention. I

An additional important point is the chemical structure of the antistatic monomer, i.e. number of moles of addition of ethylene oxide and kind of terminal alkyl or alkylphenyl radical.

A small number of moles of addition of ethylene oxide is not preferable from the point of water solubility and antistatic property. On the contrary when the number of mole of addition of ethylene oxide is too great, the molecular weight of antistatic monomer becomes too large but this is not preferable because of bad polymerization property and inferior handle of treated fibers. In other words, the number of moles of addition of ethylene oxideshould be in the range of 3 50 mol, preferably 10 40 mol.

As for the kind of alkyl or alkylphenyl group, those having 1 20 carbon atoms in alkyl group is preferable. Too greata number of carbon atoms is not only disadvantageous from the point of raw material in the commercial production but also from the points of polymerization properties, handle, and antistatic property. As examples may be mentioned methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, amyl, hexyl,

cyclohexyl, octyl, isooctyl, decyl, dodecyl, octadecyl, cetyl, oleyl, methylphenyl, ethylphenyl, butylphenyl, tertiary-butylphcnyl, octylphenyl, nonylphenyl, dimethylphenyl. Among these, it is preferable from the point of solubility of copolymer in water to make the number of mole of addition of ethylene oxide, slightly larger with the increase of the number of carbon atom of alkyl or alkylphenyl group. When the number of n is small it is preferable to make the polymerization degree of the copolymer relatively lower. In case of a monomer containing alkylphenyl group, a ratio of n/m should be 3.3 or more, preferably more than 4, where n is a number of mol of ethylene oxide added and m is a number of carbon atoms in alkylphenyl group.

When a copolymer of antistatic monomer and acrylonitrile is synthetized, it is possible to add a small amount of copolymerizable ethylenically unsaturated compound. As examples of such compound, well known esters of acrylic and methacrylic acids, vinyl esters, acrylamides, acrylic acid, methacrylic acid, vinyl monomers containing sulfonic acid, methacrylonitrile, etc. can be illustrated. These can be preferably used in an amount less than 5 percent by weight. The object of the use of these compounds lies in the improvement of polymerization properties, solubility, handle, etc.

With regard to the detail of polymerization method, both batch and continuous polymerization can be used.

Any of the organic type, inorganic and redox radical polymerization initiators can be used as a polymerization catalyst.

In the method of the present invention, it is preferable to produce a polymer in an aqueous solvent and to treat fibers with resultant solution, as it is, or after suitable dilution. From such a view point, a water-soluble redox type initiator such as ammonium persulfatesodium sulfite, ferrous salt-hydrogen peroxide or the like is preferable. Accordingly, in the preferred embodiment of the present invention, the polymerization can be easily carried out by the method in which an antistatic monomer and acrylonitrile are mixed with a suitable amount of water and dissolved therein, the total amount is charged into a reaction vessel, the above-mentioned redox type initiator is added to the mixture to effect polymerization at an elevated temperature of alternatively an increment of monomer is added little by little simultaneously with an increment of catalyst.

At this time when the polymerization is carried out with a mixing proportion of above-mentioned two monomers, the resultant polymer can be attained in the state that the water soluble property is maintained or in the state of emulsion homogeneously dispersed in water. Of course, it is possible to carry out polymerization in an organic solvent or in a solvent mixture of water and an organic solvent and then use the resultant solution, as it is, or in the state diluted with water.

The treatment of fibers with the resultant copolymer can be attained by following procedure: namely a solution of copolymer a) of suitable concentration is prepared and its PH is adjusted to 2 7, the polymer is given to tow-form fibers, staple-form fibers, spun yarns and products, by shower method or immersion method and after squeezing, drying is carried out. It is particularly preferable here that polyacrylonitrile type synthetic fibers prepared by the wet spinning process are treated with the synthetic copolymer of the present invention in the state that they have never been dried before, not even once, i.e. they are treated in the highly swollen state after being washed with water and stretched. By this method the antistatic effectiveness of treated fibers increases its wash fastness and yields a favorable result also upon handle and spinning properties. In this case, the amount of adhesion is 0.3 to 5 percent by weight of dried fibers, preferably 0.8 to 3 percent by weight of dried fibers. After adhesion, the treated fibers are dried. In this case, the drying temperature is preferably higher than 60C and lower than 150C and if necessary, a further treatment at a higher temperature under dry heat or wet heat can be effected for a short period of time. When the amount of adhesion is small, sufficient effect can hardly be attained and wash fastness is poor. On the contrary when it is too large, adhesion between each monofilament, deterioration of handle and other properties of the monofilament are liable to occur.

As above-mentioned, fibers are treated with the copolymer of the present invention, while they are in the highly swollen state, then dried, furnished with a suitable oiling agent for spinning and brought to spinning step in the tow form, as they are, or in the form of staple fibers.

In this case it is possible to produce spun yarns consisting of percent by weight of treated fibers or also possible to produce spun yarns by blending treated fibers and untreated fibers. The latter show properties which are not inferior to the former (100 percent treated products). Further the latter have the advantage in the point that handle of product can be modified or apparent proportion of adhesion can be lowered.

It does not matter even when a suitable small amount of additive e.g. a solution stabilizer, rust-proofing agent, smoothening agent, fluorescent whitening agent or the like is simultaneously used in the treating bath.

Polyacrylonitrile type synthetic fibers herein referred to are those obtained by turning a polymer containing 40 percent by weight or more of acrylonitrile into fiber form by dry or wet spinning method using an organic or inorganic solvent. By treating those fibers with the copolymer of the present invention, they are modified into the fibers which have antistatic property possessing drying fastness, and physical properties such as tenacity and dyeability which are not different from those which have not been treated, showing soft handle, and when they are made into finished products, such drawbacks as the discharging sound of static electricity at the time of undressing, clinging due to static electricity and sorption of dusts are remarkably lessened.

The present invention is further illustrated by the following non-limitative examples. All parts and percents are by weight unless otherwise indicated and antistatic effects were judged by the measurement of surface resistivity of fibers at a temperature of 20C and a relative humidity of 65 percent.

Example 1 An addition product of butyl alcohol and 20 mols of ethylene oxide was reacted with methacrylic acid using, as a catalyst, p-toluenesulfonic acid in toluene. Thus while distilling off formed water, the mixture was sufficiently esterified to give methacrylic acid ester of butyl alcohol-O mols of ethylene oxide (A). The following compositions shown in Table I were prepared by the copolymerization of the compound A and acrylonitrile TABLE 1 Number of polymer A AN Z-l 5O 50 Z-2 60 40 Z-3 7O 30 Z-4 80 20 Z-5 90 10 Z-6 95 5 Z-7 98 2 Z-8 100 The polymerization conditions were as follows:

A AN 100 parts Water 300 parts Ammonium persulfate 2 pans Ammonium hydrogen sulfite 1.3 parts pH 2-3 (adjusted by sulfuric acid) Temperature 45C Time hours After the polymerization, a translucent, viscous solution of polymer was obtained when the amount of AN was smaller, while opacity increased with the increase of AN, and in Z-l, a part of polymer precipitated in particle form; hence this case was not suitable for the treatment and it was impossible to adhere the polymer to fibers. The solutions of polymer of Z-2 to Z-8 were further diluted into 2 percent solution of polymer by adding water, and a treating solution was prepared from these solution by adding an aqueous solution of sodium hydroxide to adjust pH to 6.5. q

A copolymer consisting of 91 percent of AN, 8.5 percent of methyl acrylate and 0.5 percent of sodium allylsulfonate was dissolved in 70 percent nitric acid, and the resultant solution was extruded into a 33 percent nitric acid aqueous solution followed by the steps of washing and stretching to give undried gel-form fibers. These gel form fibers were dipped in the abovementioned treating baths, and then dehydrated by a centrifugal separator with a squeezing rate of 100 percent. It was found from the results of extraction that 2 percent of polymer per weight of dry fibers was adhered to any of the treated fibers at this stage- The treated fibers were dried in a stream of hot air at 90C for 3 hours. Treated fibers were washed for 5 minutes in a washing bath at 60C containing 0.3 percent of neutral detergent, (polyoxyethylene nonylphenol) and a cycle of washing consisting of above-mentioned washing and subsequent water washing for 5 minutes was repeated 10 times and 20 times, then the values of surface-resistivities were measured, the results of which are shown in Table 2 as values of surface-resistivities of W and W TABLE 2 Number of polymer Values of Values of surface-resistivities surface resis- As is apparent from Table 2, products treated with homopolymer of A were inferior in washing fastness of the antistatic property, whereas those treated with copolymers of A and AN were superior.

Example 2 According to the same method as that of Example 1, there were synthesized methacrylic acid esters (B) having a different number of mol of addition of ethylene oxide, expressedby the general formula,

wherein n is 2, 5, 10, 30, 50 or 80.

A monomer mixture consisting of percent of B and 15 percent of AN was fed into a flask provided with a stirrer, and water in an amount 4 times the weight of the monomer mixture, 1 percent of potassium persulfate and 0.5 percent of sodium sulfite were added. After adjustment of pH of the resultant system to 2.5 by sulfuric acid, the system was polymerized at 50C for 4 hours in'the atmosphere of nitrogen.

In case of n =2, the opacity of solution after polymerization was large, and formation of fine particles was observed, while in case of n 80, the viscosity of solution after polymerization was low, and a considerable amount of unreacted monomer was included. 7

Twelve parts of water were added to one part of the solution after polymerization, and the pH of resultant bath was adjusted to 4.0. Undried, gel-form fibers prepared in Example 1 were dipped into the bath followed by squeezing to give 1.5 percent of polymer per weight of dry fiber. The resultant fibers were dried at 70C, for 30 minutes, and then subjected to a wet heat treatment at C. The fibers thus treated were washed under the same condition as that of Example 1. The values of surface-resistivities'after 20 times washings are shown in the following Table 3.

TABLE 3 Value of surfacen resistivities of i W20 In case of n 80, treated fibers had a stiff handle and a rough feeling, and were not preferable. Example 3 Copolymers of various monomers expressed by the general formula of wherein the values of R R and n are indicated in the following Table 4, with AN, were prepared according to the conditions shown in Table 4. As shown in Table 4, ammonium persulfate (APS) and sodium hydrogen sulfite (SBS) were used as catalysts and their amounts used were expressed by weight percent per weight of total monomers. The solutions after polymerization were diluted by the same solvent as that used in the polymerization to give solutions of copolymers having 1.5 percent concentration. The pH of the solution was adjusted to 5.0 to give treating baths.

A copolymer consisting of 92.5 percent of AN, 7 percent of vinyl acetate and 0.5 percent of sodium p-styrenesulfonate was subjected to wet-spinning using dimethylacetamide as a solvent followed by the steps of stretching and washing to give undried gel-form fibers. These fibers were dipped in the above-mentioned treating baths, squeezed, to give adhered copolymers in amounts (per weight of dry fiber) shown in Table 4, and dried at 130C for 20 minutes. The fibers thus treated were washed under the same condition as that in Example 1, and the values of surface-resistivities after 20 times washings were measured. The results are shown in Table 4.

As apparent from Table 5, antistatic properties having superior washing fastness were obtained with only a small adhered amount. Further with the increase of the amount adhered, antistatic property becomes better, but in case of 5 percent of adhered amount, intermonofilament adhesion was found after wet-heat treatment, and in case of 8 percent attachment, adhesion further increased and handle was not preferable. Example 5 A solution ofa copolymer (X-l consisting of 85 percent of C and percent of AN and a solution of a polymer (X-2) consisting of 100 percent of C, were prepared according to the same conditions as those in TABLE 4 Kind of monomer Polymerization conditions Total Values of Amount monomer surface of AN in concen- Temper- Amount resistivicopolymer tration APS, SBS, ature Time attached ties of No. R; R; n (percent) (percent) Solvent percent percent 0.) (hrs.) (percent) W (o) Y-1 H CH; 30 25 30 Water 2.0 0.2 50 2 1.5 4X10 Y2 H C4Ha d0 2.0 0.2 50 2 1.5 4X10 Y3. H iso-C H 30 15 20 .....d0 2.0 1.0 40 4 1.5 8X10 Y4 CH3 1: 15 50 10 15 ..---.d0 2.0 2.0 40 4 1.5 1X10 Y-5 CH; CnHu 60 5 15 Water, 60%; 1. 0 3.0 40 4 1. 5 1X10 ethanol, 40%.

Y-6. H @011, so s 15 do 1.0 3.0 40 4 1.5 1 1o Y-7,.. II @CoI-In 40 5 15 d0 1.0 3.0 45 7 1.5 9X10 Example 4 A copolymer of AN and acrylic acid ester of an addition product of 20 mols of ethylene oxide and isopropyl alcohol (c) was prepared under following conditions:

C 85 parts AN 15 parts Water 300 parts Ammonium persulfate 2 parts Sodium hydrogen sulfite 0.4 part gH 2.2

emperature 50C Time 4 hours It was found .from the determination of unreacted monomer that 98 percent of original monomers was polymerized. Water was added to the resultant copolymer solution to give a solution having the same concentration as the adhered amount. After adjustment of pH to 3.0 by ammonia, gel-form fibers obtained in Example l were dipped in the solution, squeezed to give a squeezing rate of 100 percent dried at 100C for 30 minutes, and further subjected to a wet-heat treatment at 110C, for 5 minutes. The antistatic properties after 20 times washing of these fibers were judged. The results are shown in Table 5.

TABLE 5 Values of surface- Amount attached resistivities of Example 4, using a 5001 polymerization vessel. Each of them were diluted and their pH was adjusted to 6.

Copolymer consisting of 91 percent of AN, 8.5 percent of methyl acrylate and 0.5 percent of sodium allylsulfonate, as used in Example 1, was dissolved in percent nitric acid, and extruded into a dilute nitric acid solution, followed by the steps of water washing and stretching to give a tow. An aqueous solution containing said copolymer X-l or X-2 was given continuously to the resultant tow by shower method, to adhere X-l in amounts of 0.5 percent, 1 percent and 2 percent, respectively, and to adhere X-2 in an amount of 2.5 percent; Tows were then dried by passing through a hot air drier at 140C, subjectedto wet-heat treatment at C and further given an oiling agent for spinning. The resultant tows were spun into spun yarns via worsted spinning process using a common turbostapler, followed by knitting. The resultant knitted fabric was dyed to a camel color with a cationic dye and made up into underwear.

No marked trouble occurred during the spinning process, and the spinning could be carried out in almost the same way as in usual untreated fibers, and resultant, spun yarns showed superior fiber quality. Also, in dyeing process, articles similar or superior in coloring and dyeing evenness to usual ones could be obtained. However, underwear furnished with X-2, had a sticky feeling and were not preferable.

Underwear obtained were washed under domestic washing conditions, and thereafter, discharge sounds at the time of undressing under the conditions of 20C and 40 percent RH, were observed. Further, the values of surface-resistivities after 20 times washings under the conditions of 20C and 65 percent RH were also measured. These results are shown in Table 6.

TABLE 6 Discharge sound Alter Value of Co- Amount once After 10 After 20 surface repolymer attached Before washtimes times sistivitles, attached (percent) washing ing washings washings m X-l 0.5 7 10 X-l 1. 1 10 X-l 2. 0 x10 X-2 2. 5 1X10 N o 0 5X10 ,semis?estate. n Peieifissra Table TABLE 7 Values of surface Drying condition resistance after Amount Tempertimes Composition 0! copolattached ature Time Washing washings No. ymer (fibers) percent Sampling state (percent) 0.) (hrs) method ((2) W-l AN 81, V01; 12, AA 7. Alter stretching. 1. 5 90 1 7X10 W-2 do ..do 1. 5 90 1 4x10 10 W-3 AN 90.5, Am9, SMS 0.5., After drying 1. 0 70 0.5 8X10 W-4 Composite fibers (side After stretching. 2.0 70 2 4X10 by side type) consistof 50% AN 92.5, AM

7.1, SMS 0.4; and 50% AN 91.5, AM 3.1, AA

5, SMS 0.4.

'VClz=Viny1idene chloride. "Wet=Wet cleaning method.

No'rE.--AA-=acrylamide, SMS=Sodlum methellylsulfonete, AM=Methyl acrylate, Dry=Dry cleaning method.

Example 6 A copolymer of AN and acrylic acid ester (D) of an addition product of octyl alcohol and mols of ethylene oxide, was prepared under following conditions.

The resultant solution of copolymer was made into an aqueous solution of 2.3 percent of copolymer by adding water. A copolymer consisting of 40 percent of AN and 60 percent of vinyl chloride was dissolved in acetone, extruded in an aqueous solution of 20 percent of acetone at 20C, cold-stretched, passed through the above-mentioned aqueous solution, squeezed to give I the copolymer in an amount of 2 percent, and dried at 100C. The fibers thus treated were further stretched in a stream of hot air, and subjected to treatment under tension by means of heating rollers. The values of surface-resistivities after 20 times washings, of the fibers thus obtained was 7 X 10 whereas that of untreated fibers was 8 X 10.

Example 7 Copolymers having the compositions as shown in the following Table 7, were spun by usual nitric-acidspinning-process. After passed through the steps of water-washing, stretching, drying and after sampling under the condition indicated in Table 7, the spun copolymer fibers were furnished with the copolymer prepared in Example 4 and dried under the conditions in- What is claimed is:

1 1. A modified acrylonitrile polymer fiber containing at least 40 percent by weight of acrylonitrile monomer units as a con-stituent of the polymer and 0.3 to 5 percent, by weight of dry fiber, of an adhered copolymer consisting of 40-2 percent by weight of acrylonitrile monomer units and 60-98 percent by weight of a vinyl compound unit having a general formula of wherein R is hydrogen or methyl group, n is an integer of 3 to 50 and R is alkyl group having one to 20 carbon atoms or alkylphenyl group having one to 20 carbon atoms in alkyl group.

2. A modified acrylonitrile polymer fiber according to claim 1 wherein the acrylonitrile polymer fiber contains, in addition to the acrylonitrile monomer units, units of at least one comonomer selected from the group consisting of lower alkyl acrylates, lower alkyl methacrylates, methacrylic acid, acrylic acid, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide, methallyl sulfonates, and allyl sulfonates.

3. A modified acrylonitrile polymer fiber of claim 1 wherein said adhered copolymer contains 30-10 percent by weight of acrylonitrile monomer units and -90 percent by weight of said vinyl compound, and wherein n is an integer of 10 to 40.

4, A fibrous shaped article comprising modified acrylonitrile polymer fibers of claim 1. 

2. A modified acrylonitrile polymer fiber according to claim 1 wherein the acrylonitrile polymer fiber contains, in addition to the acrylonitrile monomer units, units of at least one comonomer selected from the group consisting of lower alkyl acrylates, lower alkyl methacrylates, methacrylic acid, acrylic acid, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, acrylamide, methallyl sulfonates, and allyl sulfonates.
 3. A modified acrylonitrile polymer fiber of claim 1 wherein said adhered copolymer contains 30-10 percent by weight of acrylonitrile monomer units and 70-90 percent by weight of said vinyl compound, and wherein n is an integer of 10 to
 40. 4. A fibrous shaped article comprising modified acrylonitrile polymer fibers of claim
 1. 